fallback to ObjectVar in guess_type

[benedikt-bartscher]

ImmutableVar.__getattr__ does not allow attribute access and guess_type does not guess ObjectVar for arbitrary objects. In our codebases, this results in a lot var.to(ObjectVar)s
this pr currently just adds a fallback. Maybe we can instead check if there is a serializer which serializes to dict?

[masenf]

@adhami3310 what do you think of this one

[adhami3310]

I'm a bit concerned here on the general case, for example, a union of an int and str might be an ObjectVar now. It feels, impure, but maybe practicality trumps correctness.

To engage more, why were you creating so many ObjectVar? Can we find a better adjustment to the API to allow this behavior be simpler as an alternative?

[benedikt-bartscher]

To engage more, why were you creating so many ObjectVar? Can we find a better adjustment to the API to allow this behavior be simpler as an alternative?

Because we often write serializers for existing objects and just want to use them in the frontend without creating an additional rx.Base "proxy class".
We could probably add some kind of marker which marks all classes which should be ObjectVars. Otherwise maybe follow my original idea from the PR description and only fallback to ObjectVar if there is a serializer registerd which serializes to dict/json.